Improvement of impact strength and toughness of polyamide resins has been made the subject matter of research and development over a considerable period of time. The tendency of articles molded of polyamide resins to crack or break upon impact, in a brittle fashion, imposes a serious limitation on the ability to make use of such molded articles, especially at low temperatures.
The endeavors to improve impact strength and toughness has led to the blending of the polyamides, with a variety of additives including rubbers and other modified and unmodified resins with various degrees of success. One such recent endeavor is described in the Epstein U.S. Pat. No. 4,174,358, issued Nov. 13, 1979, wherein polyamide resins are blended with random copolymers selected to adhere to the polyamide resin. The Epstein patent does not address the issue of impact strength at low temperatures, and it does not recognize the advantages derived from the use of low molecular weights for blending with the polyamide resins.